7.10 Section 2.4, The method of variation of parameters. Page 154

7.10.1 problem 1
7.10.2 problem 2
7.10.3 problem 3
7.10.4 problem 4
7.10.5 problem 5
7.10.6 problem 6
7.10.7 problem 7
7.10.8 problem 8
7.10.9 problem 11
7.10.10 problem 12